Research Article Maintaining Mobile Network Coverage Availability in Disturbance Scenarios Joonas Säe and Jukka Lempiäinen Department of Electronics and Communications Engineering, Tampere University of Technology, Tampere, Finland Correspondence should be addressed to Joonas S¨ ae; joonas.sae@tut.f Received 11 July 2016; Accepted 22 September 2016 Academic Editor: Ioannis Moscholios Copyright © 2016 J. S¨ ae and J. Lempi¨ ainen. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Disturbance and disaster scenarios prevent the normal utilization of mobile networks. Te aim of this study is to maintain the availability of cellular networks in disturbance scenarios. In order to extend the disaster time functionality, energy usage optimization is needed to maintain reasonable coverage and capacity. Simulations performed with diferent network layouts show the efects of choosing only a portion of evolved node B (eNB) macrosites to operate at a time. Diferent sets of three to nine three- sectored eNB sites are selected to study how the network would perform with a limited number of eNB sites. Simulation results show how the mobile network availability duration can be sustained by selecting a set of eNB sites to operate at a time and still maintain a reasonable service level and availability in disturbance scenarios. An increase of 100% to 500% can be achieved in the duration of “backup coverage” in cellular networks with backup batteries when the percentage of active eNB sites is reduced down to 20%. 1. Introduction Disaster and disturbance scenarios usually occur without a warning. Whether they are natural weather-based storms or disasters caused by human, such as accidents or sabotage, the efects can be devastating and usually prevent the normal utilization of mobile networks. Typically, storms are the cause of blackouts in electrical grids [1]; furthermore, they have an impact on public safety and commercial mobile networks, thus yielding service and communication outages in urban and rural areas. Tis can eventually prevent citizens from requesting emergency help in these outage areas. In addition, maintenance and rescue teams can not communicate through commercial mobile networks and have to have a separate communication system. Service outages in mobile networks are mainly caused by (storm-related) power outages. In order to enable some service in these cases, evolved node B (eNB) macrosites are typically supplied with backup batteries. Tese reserve energy resources provide power to run eNBs, but only for a limited time period. In Finland, this corresponds to 2–4 hours, as required by the Finnish Communications Regulatory Authority [2]. Afer strong weather phenomenon, in the worst case, the repair-work may take several days resulting in the unavailability of commercial cellular networks that may also endanger rescue operations. An alternative is to have aggregates over the network or at certain critical eNB sites, to guarantee their electricity supply for a longer period of time. Because aggregates are slightly costly to be supplied and used at every site, some optimization is needed in a similar way as in the case of battery backups; that is, how many aggregates should be enough to enable sufcient cellular network cov- erage? Moreover, in case of longer term of electrical cut-ofs (i.e., over one day), aggregates are eventually required to guar- antee (cost-efcient) mobile network communications in disturbance scenarios. Another type of critical discontinuity in mobile networks may happen due to major malfunctions in the core transmis- sion network, major damage in the core network elements, such as controllers, or in the switching functions. Tese malfunctions can also be caused by sabotage or a cyberattack, which may cause very wide discontinuity in the whole mobile Hindawi Publishing Corporation Mobile Information Systems Volume 2016, Article ID 4816325, 10 pages http://dx.doi.org/10.1155/2016/4816325